As demand for bandwidth increases for cellular communications, in particular for data packet transfers, allocation of resources within the limited bandwidth available becomes more difficult. In order to be useful, the allocation needs to satisfy a number of often conflicting, and not necessarily well defined, criteria. Such criteria include a concept of fairness, where all users requiring a data packet transfer service are allocated the limited packet resources on a generally “equal” basis. In such a fair distribution of resources no specific user is allocated substantially more or less resources than an “average” allocation, in any time frame where the allocation is performed. The concept of fairness may be applied to users having very different transmission and reception conditions, for example by allocating more resources to a user with poor reception conditions. Application of a particular fairness concept to a group of users may have to take into account, inter alia, different levels of service to which users in the group are entitled, for example, by some of the users in the group having subscribed to a premium service.
A further criterion applied in allocating resources is maximization of throughput rate. It will be appreciated that total throughput rate and fairness typically conflict. As an extreme example, to achieve maximum throughput rate, all resources may be allocated to a user having good reception conditions who is thus able to receive data at a high rate, with no resources being allocated to a user who is able to receive data only at a low rate. Such an allocation achieves maximum throughput rate at the expense of a completely unfair allocation.
Other criteria which an efficient bandwidth allocation system should consider include ability to react quickly to changing demands and conditions, a minimum transfer of management or related resources, and a relatively simple design to limit implementation risks.
Systems for allocating bandwidth for data packet transfer according to some of the above criteria are known in the art. For example, U.S. Pat. No. 6,449,490 to Chaponniere, et al, whose disclosure is incorporated herein by reference, describes a method for determining to which users access to a communication system is to be provided. The description takes into effect both fairness and throughput rate criteria described above.
U.S. Pat. No. 6,657,980 to Hotzmann, et al, whose disclosure is incorporated herein by reference, describes a method for scheduling packet data transmissions where a user priority function is based on a channel condition indicated by data rate requests. The method also considers fairness criteria dictated by predetermined Quality of Service requirements.
Notwithstanding the above, an improved allocation system which takes account of all the criteria described would be advantageous.